1. Field of the Invention
The present invention relates generally to wheelchairs and more particularly to an anti-rollback assembly that operatively associates with a wheelchair to prevent the wheelchair from rolling backwards and away from its occupant as the occupant attempts to mount or dismount the wheelchair, yet permits the wheelchair in an unoccupied state to be moved in a forward direction.
The anti-rollback assembly of the present invention is especially suitable for wheelchairs of invalids, the cognitively impaired, the elderly, and sufferers of physically and mentally disabling diseases such as Alzheimer""s.
2. Description of the Related Art
Almost all wheelchairs possess a parking brake in one form or another which, when actuated, maintains the wheelchair in a stationary position by preventing one or both of the large drive wheels of the wheelchair from rotating about a common central axis. Perhaps the most crucial periods for the wheelchair to remain stationary are when a person attempts to sit down in and occupy the wheelchair and when the occupant attempts to stand up from and vacate the wheelchair. The natural motion of a person performing these acts imparts a force in the rearward direction on the wheelchair, which, without the benefit of an actuated parking brake, causes the wheelchair to move backwards and away from the person.
As a consequence of the mental and physical infirmities suffered by many wheelchair occupants, especially patients suffering from Alzheimer""s disease and other mental frailties, occupants often forget to actuate manually-operated parking brakes prior to attempting to rise from the wheelchair, or neglect to inspect the parking brake to ensure it is engaged in a locked position prior to attempting to sit down into the wheelchair. Failure to engage the manually-operated parking brake in its locked position presents a serious hazard of injury to both the occupant and his or her caretaker, since the wheelchair is unimpeded from rolling back and away from the occupant as the occupant attempts to rise from or sit down in the wheelchair.
To address the shortcomings of manually-operated parking brakes, several different automatically-operated locking brake assemblies have been proposed. U.S. Pat. No. 5,203,433 sets forth a discussion of some conventional automatic locking brake assemblies. Each of the conventional assemblies mentioned in U.S. Pat. No. 5,203,433 is characterized by the provision of a locking member that, unless manually disengaged, prevents or at least substantially obstructs both the forward or rearward movement of the wheelchair with which the assembly is associated when the wheelchair is unoccupied.
However, one of the most important functions served by an automatic wheelchair brake is that it not only prevent the wheelchair from rolling backwards and away from its occupant as the occupant mounts or dismounts the wheelchair, but that the brake also not substantially obstruct the forward motion of the wheelchair when unoccupied so that the unoccupied wheelchair can be easily maneuvered to a desirable location for use or temporary storage.
A long-felt need therefore exists to provide an automatically-operated anti-rollback assembly for a wheelchair that biases a braking mechanism into an activated position when the wheelchair is unoccupied to prevent the wheelchair from rolling back when it is mounted or dismounted in normal operation, yet, while in the activated position, permits the forward motion of the unoccupied wheelchair.
It is, therefore, an object of the present invention to provide an anti-rollback assembly that solves the aforementioned problems associated with the related art as well as other problems and addresses the long-felt need outlined above.
It is another object of the present invention to provide an automatic anti-rollback assembly which is reliable in operation, easy to use, and economical to manufacture.
A further object of the present invention is to provide an automatic anti-rollback assembly that can be easily and inexpensively retrofitted to existing wheelchairs.
It is another object of the present invention to provide an automatic anti-rollback assembly that, when operatively associated with a wheelchair, permits the unoccupied wheelchair to freely roll in a forward direction, yet impedes only the rearward motion of the wheelchair, so that the unoccupied wheelchair can be used, for example, as a walker.
Still another object of the present invention is the provision of a wheelchair having an automatic anti-rollback assembly with an ambulation monitor which activates an alarm when the wheelchair occupant attempts to vacate the wheelchair.
In accordance with the principles of the present invention, these and other objects are attained by the provision of an automatic anti-rollback assembly that is adapted or adaptable for use in combination with a wheelchair. The automatic anti-rollback assembly generally comprises a one-way brake assembly supportable on a frame structure of a wheelchair, biasing member, and a brake releasing assembly. The one-way brake assembly includes a one-way brake member (or brake arm). When used in combination with a wheelchair, the one-way brake assembly is movable between a non-activated position in which the one-way brake member is positioned to permit the rear drive wheel assembly to rotate in forward and rearward directions to enable the wheelchair to move freely in both the forward and rearward directions, and an activated position in which the one-way brake member is positioned to prevent rotation of the rear drive wheel assembly in the rearward direction so as to prevent movement of the wheelchair in the rearward direction, yet continues to permit rotation of the rear drive wheel assembly in the forward direction for forward movement of the wheelchair. The biasing member serves to impart a biasing force to urge the one-way brake assembly towards the activated position. The brake releasing assembly is operatively associated with the one-way brake assembly and the biasing member, and is movable in response to the wheelchair being occupied to overcome the biasing force of the biasing member so as to move the one-way brake assembly from the activated position to the non-activated position, thereby enabling the wheelchair to freely move in both the forward and rearward directions unencumbered by the one-way brake member.
In accordance with the present invention, the occupant of the wheelchair is not required to set a conventional parking brake. Instead, the wheelchair is automatically immobilized against backward movement by the anti-rollback device when the occupant is attempting to rise from or sit himself in the seat member. In addition, when the occupant is fully seated in the seat member, the anti-rollback device is disengaged, i.e., the one-way brake assembly is moved into a non-activated position, so that the wheelchair can be freely moved forward or backwards unencumbered by the one-way brake member.
These and other objects, features, and advantages of the present invention will become apparent from the following detailed description when taken in conjunction with the accompanying drawings which illustrate, by way of example, the principles of the present invention.